In the field of heater exchangers and chemical reactors, tubing is often used. For example, in cracking furnaces and heater exchangers, there are parallel tubes connected to each other at their ends using bends, such as U-bends or other types of bends, to form a continuous tube. Fluid typically flows through the piping while the chamber or environment around the piping is heated to heat the fluid flowing within the piping.
In a tubular reactor for cracking, a furnace houses banks of tubes that are connected to each other to form one or more continuous tubes for fluid to flow through. The tubes may form a serpentine configuration. Furnace guns or heat generators, for example, surround the banks of tubes.
Similarly, in a heater unit, a series of straight and parallel tubes are connected to each other using U-bends or other types of bends to make a continuous tube for fluid to flow through.
The straight parallel portions of the tubing are typically positioned close together to reduce the amount of space being used within the furnace or the heat exchanger. There may be dozens to hundreds of straight portions of tubes. The inner diameter of the tubes typically range from under one inch to several inches.
Access to the tubes is difficult and therefore cleaning the tubes is difficult. Deposits, scales, product or by-product build-up, and material in general will collect on the inner surfaces of the tubes, thereby reducing the flow of fluid within the tubes.
To clean the inner surfaces of the tubes, it is generally known that pigs are sent through the tubes under high pressure liquid. For example, pigs with scraping implements or brushes are sent through the tubing one at a time.
U.S. Pat. No. 4,545,426 describes spherical turbulators that slide along a string and are positioned within a tube of a heat exchange to induce turbulent flow. The string of turbulators stay within the tube and is not meant to be moved or pulled through the tube. The stopper beads limit the distance that the turbulators may slide along the string. The stopper beads, and therefore the turbulators, are positioned at least a factor of n times more than the diameter of the tube. It is herein recognized that it would be difficult to pull the string of turbulators through a U-bend since the string or the turbulators may catch on the U-bend surface of the tube.
U.S. Pat. No. 6,332,930 describes a large diameter pipeline cleaning arrangement with a cable pulling guide units and a pig. Only a small length of cable has guide units, and each of the guide units include three curved shoes.
U.S. Pat. No. 2,99,493 describes a pipe cleaning device for large diameter pipes, and a method that includes alternatively releasing and pulling different cables to work the device in opposite directions at any location along the pipe.
U.S. Pat. No. 4,715,747 describes an air-motivated cone that tows a mandrel through a conduit. The mandrel includes a series of plates that are spaced apart from each other. Following the mandrel is considerable length of rope or cable.
U.S. Pat. No. 4,827,533 describes an apparatus that moves a pipe cleaning device in opposite linear directions. The cleaning device includes a linear body formed from rigid tube or pipe, which would not be suitable for navigating bends.
U.S. patent application publication no. 2012/0031609 describes low friction wireline standoffs used for during borehole logging operations. The standoffs are oblong shaped and are typically positioned 10 ft to 100 ft apart from each other.